1. Technical Field
The present invention relates to an electronic timepiece with an internal antenna.
2. Related Art
Japanese Unexamined Patent Appl. Pub. JP-A-H09-307329 teaches an electronic timepiece having a loop antenna 20 formed along the outside circumference below the crystal 5, and lugs 2 for attaching a wrist band at the 12:00 and 6:00 positions of the case 1. As shown in FIG. 1 of JP-A-H09-307329, an electrode 21 for the antenna 20 is also disposed near one of the lugs 2, that is, the electrode 21 of the antenna 20 is disposed at 12:00 or 6:00.
Japanese Unexamined Patent Appl. Pub. JP-A-H09-247006 discloses disposing an antenna 11 that functions as a loop antenna in unison with the case 17 of a wrist-worn receiver. As shown in FIG. 1 of JP-A-H09-247006, lugs 21 for attaching a band 41 are formed at two locations on the case 17, and a feed opening 15 for the antenna 11 is disposed near one set of lugs 21.
Because signals from GPS (Global Positioning System) satellites cannot be received indoors, an electronic wristwatch must receive signals from GPS satellites when the user is outdoors. When outdoors, the arm of the user on which the wristwatch is worn is often hanging down at the side or in front of the user's body. In this posture, the normal direction of the face of the wristwatch is horizontal. For example, with an annular (O-shaped) loop antenna or a C-shaped loop antenna having part of the ring missing, radiant directivity in the plane including the loop plane is greatest at or near the direction in which the feed electrode is disposed as seen from the center of the ring. Therefore, arm of the user on which the wristwatch is worn hanging down or held in front of the body, sufficient reception performance cannot be achieved with the loop antennae disclosed in JP-A-H09-307329 or JP-A-H09-247006 because the direction of maximum radiation where antenna gain is greatest is the direction parallel to the band, that is, towards the horizon instead of the zenith.